Geoscience Reference
In-Depth Information
4- Conclusion and future plans
The aim of this paper is to present a best practice approach for the gener-
alisation of polygon data from medium to small scale in a GIS environ-
ment taking into account inter-theme consistency. The use of the map
overlay operations as a tool to solve integrity problems of the original data
and to create structural knowledge supportive for generalisation is pro-
posed. An auxiliary dataset is used to solve the integrity problems of the
original datasets, to simultaneously simplify the geometry ensuring no in-
consistency problems and to better handle other cartographic generalisation
issues such as minimum area imposed by the limits of visual perception. In
addition to this a generic modeling issue is discussed that addresses the
duality between the polygonal units and their linear borders. An appropriate
data model to link units and borders is proposed based on topological rela-
tionships. Generalisation of themes that are represented with polygons and
lines in the spatial database is successfully handled based on topological
relations.
The above-described best practice approach has been applied and tested in
the framework of the ESDIN project. A number of rules developed in the
framework of the ESDIN project for the generalisation of Administrative
Units, Built-up Areas and Watercourse areas have been successfully util-
ized. A tool has been created in a standard based GIS, that implements the
generalisation rules with the help of the proposed methods. The case study
has proved that EGM can be extracted from ERM based on rules, although
these datasets are created in different environments and are based on dif-
ferent national products. In addition to this, the value of the introduced
best practices for the generalisation of polygon data has been verified.
Acknowledgments
This work has been done in the framework of the ESDIN project (European Spatial Data Infra-
structure with a Best Practice Network - http://www.esdin.eu/). ESDIN is supported by
eContent+ programme and is coordinated by Eurogeographics.
